In general, a fuel cell (e.g., a solid polymer electrolyte fuel cell) is configured by laminating a plurality of cells in each of which an electrolyte is sandwiched by separators. In such a fuel cell, if produced water or condensed water remains in a flow path, etc. in the separators, such water will freeze at a low temperature, which might cause, in some cases, electrolyte membranes, separators, pipes, valves, etc. to be broken. Furthermore, if frozen water blocks a gas flow path, the supply of gas will be hindered when the fuel cell is started next time, which might hinder an electrochemical reaction from progressing sufficiently. In light of such circumstances, in related art fuel cell systems, so-called scavenging processing for removing water remaining in a fuel cell is performed by, for example, sending dry air into the fuel cell when, for example, the operation is ended (for example, see patent document 1).
Patent document 1: Japanese laid-open patent publication No. 2007-157621